biology

Permissive cell

Permissive cell is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Permissive cell rather than just read about it. In short: A permissive cell or permissive host is one that allows a virus to circumvent its defenses and replicate. Usually this occurs when the virus has modulated one or several of the host cellular intrinsic defenses and the host immune system.

Key takeaways

Permissive cell belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Permissive cell to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Permissive cell from memory before moving on to harder problems.

Reference excerpt

A permissive cell or permissive host is one that allows a virus to circumvent its defenses and replicate. Usually this occurs when the virus has modulated one or several of the host cellular intrinsic defenses and the host immune system. The permissive state of a host has now been determined to be the primary factor in determining whether a virus will cause pathological symptoms in a host.

Susceptible versus permissive A virus can enter a susceptible cell, but it may or may not be able to replicate. A virus may only replicate in a permissive cell. Viral replication will therefore occur in a susceptible cell which is also a permissive cell that 1) facilitates entry (susceptibility) and 2) supports intracellular replication (permissive cell). The significance of the difference between the two has now been elucidated with study of the rabbit-lethal myxoma virus. Many species of rabbit cells in culture (without the presence of any antiviral defenses that would normally be in a host) can be infected by the myxoma virus, causing infection and cell death. However, inoculation of the myxoma virus in many species of rabbit shows that only one species of rabbit is affected, the rest being completely unharmed by the virus (lack of even viral shedding). This has been determined to be a result of the myxoma virus's inability to suppress other species' interferon expression, and hence resulting in the interferon in turn suppressing the myxoma virus. This is a result of the positive susceptibility of many species of rabbit's cells, but negative permissibility of all but one of the rabbit species' cells.

Literature

Worked examples

Example 1 — a first encounter with Permissive cell

Start with the simplest possible case. Write down what Permissive cell claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Permissive cell before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Permissive cell ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Permissive cell

In research: Permissive cell appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Permissive cell in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Permissive cell is common in secondary-school and first-year university syllabi. It links to neighbouring topics Virology, so understanding it makes those chapters shorter.
In everyday life: Look for Permissive cell outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Permissive cell in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Permissive cell means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Permissive cell out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Permissive cell in simple terms?

Why does Permissive cell matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Permissive cell?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Permissive cell.